The present invention relates to control apparatus, and more particularly (though not exclusively) to apparatus which generates control signals or data values in response to inputs which may be manual or derived from some other source including, but not limited to industrial sensors such as thermocouples, photo-electric, flow proximity etc.
There are many situations where it is desirable or necessary to control two or more entities simultaneously by suitable electrical signals. If two such signals are required, one standard manual technique is to provide a joystick. There are many applications of joysticks, ranging from computer games to adjustment of car door rear-view mirrors to the control of vehicles. Other systems, in the process control industry for example, will take inputs from sensors and use them via a process control system to produce control data which is applied to the application to keep it stable, or operating within desired parameters. This invention, once programmed (a process that happens in existing process control systems) will control the application without operator intervention, if required.
The invention provides control signal generating apparatus for generating a first plurality of output signals from a second plurality of input signals. For each output signal, locus generating means define a sequence of combinations of values corresponding to the input signals forming a locus in the space defined by the input signals; and for each locus generating means, there is a distance value signal calculator for evaluating an output signal having a value determined by the distance in said space of the point (the cursor point) represented by the combination of input signal values relative to the locus.
Preferably, the distance value is the distance along the locus corresponding to the projection of the point onto the locus and the locus is a linear locus (as contrasted with a 2-dimensional or higher-dimensional locus). A locus may be a straight or curved line (which may form a closed loop), and may consist of two or more separate segments.
Setting means may be provided for adjusting the loci defined by the locus generating means.
Preferably there is an input device controllable by an operator to generate the second plurality of input signals, and a display device for displaying the cursor point and, for each locus generating means, the locus defined thereby. The display device preferably also displays, on each locus, the projection of the cursor point onto that locus. The input device may include switch control means for controlling, e.g., when the apparatus responds to changes in the input signals, or for controlling the mode of operation of the apparatus.
The number of dimensions of the space defined by the input signals will be the same as the number of input signals, and can conveniently be a Euclidean space. If there is no display device, then the space will be an abstract or conceptual space; if there is a display device, then the space will be real in the sense that it is displayed by the display device. The display device may display the space in a reduced or projected form, e.g. if the space is 3-dimensional and the display device is 2-dimensional.
The apparatus may be used to compress a set of variables corresponding to the number of output signals. For this, the set of variables is compared with the set of output signals, and the input signals are adjusted to reduce the difference therebetween. The set of input signals will therefore represent the set of variables. If the number of input signals is chosen to be less than the number of output signals (i.e. the number of variables in the set of variables), a data compression will thereby be achieved. The apparatus may similarly be used to reverse this process.
The system may be implemented on a general-purpose computer. The system may also be implemented using Field Programmable Gate Arrays (FPGA), Application Specific Integrated Circuits (ASIC), microcontroller circuitry or similar technology.